1Heat 2 tablespoons of oil in a medium saucepan over medium heat. Add onion, garlic, chilli and thyme. Reduce heat to low; cook, stirring occasionally, for 30 minutes or until onions are soft and caramelised.
2Preheat oven to 200°C/400°F. Line an oven tray with baking paper.
3Place tomatoes, zucchini and eggplant on lined tray, drizzle with vinegar and remaining oil; season. Bake for 20 minutes or until vegetables are browned. Remove from oven and increase oven temp to 220°C/425°F.
4Line a 20 x 30 cm (8 x 12 in) slice pan with baking paper, extending the paper 2 cm (¾ in) over sides. Thaw pastry then join sheets together to form a long rectangle.
5Place tomatoes, cut-side down, on base of lined pan with zucchini and eggplant to fit snuggly, side by side. Top with caramelised onion and half the basil leaves.
6Place pastry over the vegetables and trim if necessary, leaving enough to tuck in around the inside edges of the pan.
7Bake tart for 25 minutes or until pastry is puffed and golden. Leave in the pan to cool for 5 minutes.
8Place a board or platter large enough to cover the pan over the tart; flip tart onto board, then remove the lining paper.
9Drizzle tart with extra olive oil and top with remaining basil. Cut tart into four wedges, and eat soon after baking, while the pastry is still crisp and warm!
Tip: Serving suggestion: Top with vegan feta and serve with a side salad!